Method and Apparatus for Utilizing Synchronization Information

ABSTRACT

A communication method and system are provided that include providing synchronization information about a co-sited downlink carrier. This information may be transmitted to from a base station to a mobile device. The mobile device may receive this information and perform handover or measurements based on the received synchronization information.

The application is a continuation of U.S. patent application Ser. No.10/424,934 to Schwarz, et al. filed Apr. 29, 2003 entitled, “Method andApparatus for Utilizing Synchronization Information” which claimspriority from U.S. Provisional Patent Application Ser. No. 60/375,831filed Apr. 29, 2002, the subject matter of which is incorporated hereinby reference.

TECHNICAL FIELD

This invention relates to wireless telecommunication systems. Morespecifically, the present invention relates to utilizing synchronizationinformation for co-sited downlink carriers.

BACKGROUND

Wireless communication systems are widely deployed to provide varioustypes of communication such as voice, data, and so on. These systems maybe based on code division multiple access (CDMA), time division multipleaccess (TDMA), or some other modulation and multiple access techniques.In the development of third generation systems, cdma2000 and WCDMA, bothCDMA systems, have emerged as competing technologies. Like earliergenerations of CDMA, cdma2000 and WCDMA support soft handover. In softhandover, a mobile station such as cellular phone communicates via twoor more base stations at one time. Techniques available for making softhandover depend upon the synchronization of base stations in the system.

SUMMARY OF THE INVENTION

Embodiments of the present invention may provide a communications methodthat includes obtaining synchronization information about a downlinkcarrier and performing an operation (such as handover or measurements)based on the obtained synchronization information. The downlink carriermay be a co-sited downlink carrier. The synchronization information maybe provided based on a status bit or a plurality of bits. Thesynchronization information may indicate relative synchronizationbetween downlink carriers.

Embodiments of the present invention may also include a communicationsystem that includes at least one network device in a communicationsnetwork and a mobile device operatively connected to the communicationsnetwork. The at least one network device may provide synchronizationinformation about a downlink carrier, and the mobile device may performan operation based on the obtained synchronization information.

Other embodiments and features of the present invention will becomeapparent from the following detailed description taken in conjunctionwith the annexed drawings, which disclose preferred embodiments of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention will become apparentfrom the following detailed description of example embodiments and theclaims when read in connection with the accompanying drawings, allforming a part of the disclosure of this invention. While the followingwritten and illustrated disclosure focuses on disclosing exampleembodiments of the invention, it should be clearly understood that thesame is by way of illustration and example only and that the inventionis not limited thereto.

The following represents brief descriptions of the drawings in whichlike reference numerals represent like elements and wherein:

FIG. 1 is a diagram of a system according to an example embodiment ofthe present invention;

FIG. 2 is a diagram of an example interface scenario in an uplinkchannel according to an example arrangement;

FIG. 3 is a diagram of another example interface scenario in an uplinkchannel according to an example arrangement;

FIGS. 4A and 4B are diagrams showing uplink and downlink carrierpairings according to example arrangements; and

FIG. 5 is a flowchart showing operations according to an exampleembodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The particulars shown herein are by way of example and for purposes ofillustrative discussion of arrangements and embodiments of the presentinvention. The description taken with the drawings make it apparent tothose skilled in the art how embodiments of the present invention may beembodied in practice.

Further, arrangements and embodiments may be shown in block diagram formin order to avoid obscuring the invention, and also in view of the factthat specifics with respect to implementation of such block diagramarrangements may be highly dependent upon the platform within which thepresent invention is to be implemented. That is, these specifics shouldbe well within the purview of one skilled in the art. Where specificdetails (e.g., flowcharts) are set forth in order to describe exampleembodiments of the invention, it should be apparent to one skilled inthe art that the invention can be practiced without these specificdetails.

Embodiments of the present invention may relate to a communicationsmethod for a Wideband Code Division Multiple WCDMA Access system,although other types of systems are also within the scope of the presentinvention. The method and network may provide synchronizationinformation about a downlink carrier and transmit that information to amobile device. The mobile device may thereafter perform a handover orinter-frequency measurements, for example, based on the receivedsynchronization information. That is, the synchronization informationmay be used for fast and efficient measurements (Ec/IO or RSCP) or forUE synchronization (i.e., faster blind handovers). The synchronizationinformation may be in the form of a single bit or a plurality of bits.This may be especially useful because when WCDMA carriers are co-sited,the downlink transmissions are synchronized (and possibly even chipsynchronized). Thus, mobile devices making measurements on anothercarrier or handing over to another carrier may use this synchronizationinformation to make the measurement/handover faster.

FIG. 1 shows a diagram of a system according to an example embodiment ofthe present invention. Other embodiments and configurations are alsowithin the scope of the present invention. The system includes atelecommunications network 10 that includes network devices or nodes12-22 and mobile devices (e.g., user equipment (UE), mobile nodes (MN),mobile stations (MS), etc.) 3048. The terms mobile device, mobile node,and user equipment may be used interchangeably throughout thisdisclosure to refer to the same type of device.

The network devices 12-22 may be any type of network node or device thatsupports wireless devices connected to a telecommunications network, forexample, a Radio Network Controller (RNC), a Base Station Controller(BSC), etc. The network device 12 and the mobile device 36 transfer dataand control information between each other via uplink channels 35 anddownlink channels 37. A base station or cell (not shown) may supplyfrequencies from a particular band of frequencies (e.g., a 2 GHz coreband or 2.5 GHz extension band) that allow the mobile device 36 toselect from and use for a downlink carrier and uplink carrier. Theuplink carrier frequency and downlink carrier frequency may be from thesame band of frequencies, or from different bands of frequencies.

As a mobile device moves from one location to another, the base stationor cell closest to the mobile device will likely then supply the uplinkand downlink carriers for the particular mobile device. Generally, ifthe same band of frequencies is available at the neighboring basestation, the network device may direct a soft handover to occur betweenthe downlink and uplink carriers supplied from the original base stationto downlink and uplink carriers supplied from the neighboring basestation. Handoff between different base stations may depend uponsynchronization information (such as time difference) between basestations.

A currently used network device 12 and/or neighboring network device 14,possibly along with the mobile device 36, may detect soft handover areasbefore a handover is to occur such that a handover may occur withoutcausing uplink channel interference. Uplink interference may be causedwhen a mobile device moves to a location that does not supply the samebands of frequencies currently being used by the mobile device for itsdownlink carrier.

Each of the mobile devices 30-48 and/or the network devices 12-22 mayperform various measurements in a periodic or continuous basis to detectsoft handover areas for uplink interference avoidance. For example,measurements such as signal strength, signal quality, etc. may be madeand compared with similar measurements of carriers from neighboring orco-sited bands to determine if a soft handover area exists and whether ahandover should occur to avoid uplink interference. A network deviceand/or mobile device may determine the types of measurements made andwhen they are made. Moreover, a network device and/or mobile device mayperform the measurements, where in the latter case, a network node mayinstruct the mobile device to perform the measurements or the mobiledevice perform the measurements without instruction from the networkdevice. Further, the mobile device may perform the measurements andreport the results to the network device whereby the network devicedecides whether a soft handover area exists and whether a soft handovershould occur to avoid uplink interference.

Signal quality of a carrier (downlink or uplink) may includeinterference from other cells and may be related to the signal qualityat a specific mobile device. In contrast, signal strength may includethe sum of all the signals and indicate the total strength in a specificfrequency. With signal strength measurements, there is nodifferentiating between a particular mobile device's signal and othersignals. Co-sited downlink (DL) carriers are downlink carriers from thesame antenna or same base station or cell as the downlink carriercurrently being used by a mobile device.

Measurement of the relative signal quality may also be performed. Inthis method, signal quality may be measured and compared with the signalquality of downlink carriers from another base station. Differencesbetween the two may then be used to determine if a soft handover areaexists. Moreover, a mobile device currently using a current downlinkcarrier from a current cell and moving closer to a neighboring cell maylook for a downlink carrier from the neighboring cell from the samefrequency band as the current downlink carrier. If a downlink carrier ismissing in this band, then the network device and mobile device knowthat a soft handover area exists where uplink interference may occur ifthe handover doesn't occur earlier.

Soft handover area detection may occur while a mobile device is in anymode or state, for example, the mobile device may be in an idle mode, ora connected mode where it is waiting for data or actively transmittingdata. Depending on the mode or state of the mobile device, may determinewhat types of measurements (e.g., inter-frequency measurements) may bemade.

One reason for handover may be because the mobile device has reached theend of coverage of a frequency carrier in an extension (e.g., 2.5 GHz)band. The end of extension band coverage may invoke inter-band,inter-frequency or inter-system handover. The trigger criteria mayalways be the same. As inter-band handovers can possibly be done faster,separate trigger thresholds might be implemented. Some example coveragetriggers for example arrangements may include, but are not limited to:handover due to Uplink Dedicated Channel (DCH) quality, handover due toUE Tx power, handover due to Downlink Dedicated Physical Channel (DPCH)power, handover due to common pilot channel (CPICH) received signal chippower (RSCP), and handover due to CPICH chip energy/total noise (Ec/No).Handover is functional to keep a connection from being dropped while themobile terminal is moving from one cell to another cell of the network.

Coverage may be another reason for handover. A coverage handover mayoccur if: (1) the extension band cell has a smaller coverage area(=lower CPICH power or different coverage triggers) than a core band,(2) currently used core band coverage ends (then also extension band),or (3) the UE enters a dead zone.

Intra-frequency measurements may be another reason for soft handover. Asoft handover (SHO) procedure in an extension band may work in principlethe same way as in core bands with branch addition, replacement anddeletion procedures. SHO procedures may be based on CPICH Ec/IOmeasurements. Despite stronger attenuation in the extension band, Ec/IOas a ratio may be about the same for both bands. Therefore, in principlethe same SHO parameter settings may be used in the extension band.However, if stronger attenuation in an extension band is not compensatedfor by additional power allocation, the reliability of SHO measurements(Ec/IO) may suffer. Moreover, an extension band cell might haveneighbors on extension band frequencies and on core band frequencies atthe same time. Then, the UE may have to measure both intra-frequency andinter-band neighbors.

UL interference in the core bands due to delayed SHO at the extensionband coverage edge may occur. An extension band cell may have bothextension band neighbors and core band neighbors at the same time. Whilefor the extension band neighbor the normal SHO procedure may besufficient, for the core band neighbor an early enough inter-bandhandover may have to be performed. Otherwise, serious UL interferencecould occur in the core band neighbor cell. SHO areas might be locatedrelatively close to the base station and thus not necessarily relate tohigh UE Tx (transmit) power (or base transceiver station (BTS) Txpower). Coverage handover triggers may not be sufficient.

FIG. 2 shows a diagram of a potential interface scenario in an uplinkchannel according to an example arrangement. Other arrangements are alsopossible. Three cells or base stations 51, 53, 55 are shown with slightintersection between neighboring (adjacent) coverage areas. The leftmostcell 51 supplies two co-sited bands of frequencies, an extension band offrequencies 60 and a core band of frequencies 54. The middle cell 53also supplies two co-sited bands of frequencies, an extension band offrequencies 52 and a core band of frequencies 56. The rightmost cell 55only supplies a core band of frequencies 58.

In this example arrangement, a mobile device (UE) 50 is using a downlinkcarrier from an extension band of frequencies 52 from the base station53 closest to the mobile device 50. As the mobile device 50 moves fromthe left side of base station 53 and approaches cell coverage overlapareas, the mobile device 50 uses UL and DL carriers from neighboringcells (i.e., middle cell 53 and rightmost cell 55). Generally, if themobile device 50 is using an UL and DL carrier in an extension band(e.g., a band of frequencies starting at approximately 2.5 GHz) cell,once the mobile device 50 moves towards the coverage of a neighboringextension band cell, a soft handover will occur between the DL and ULcarriers of the neighbor cells. However, in a situation where there isno neighboring extension band cell as shown here, a soft handover cannotoccur since the mobile device 50 must now obtain a DL and UL carrierfrom a core band (e.g., a band of frequencies starting at approximately2 GHz) cell. This may cause interference in the UL carrier (not shown)of the neighboring cell. However, a network device may monitor thissituation and cause selection of a different DL carrier in an existingband early to allow a soft handover from the extension band (e.g., 2.5GHz) in middle cell 53 to the core band 58 (e.g., 2.0 GHz) in theneighboring cell 55, therefore avoiding potential interference in the ULcarrier of the neighboring cell 55.

FIG. 3 shows a diagram of another potential interface scenario in anuplink channel according to an example arrangement. Other arrangementsare also possible. In this example, the mobile device (UE) 50 is using adownlink carrier from a core band of frequencies 58 from the basestation 55. The mobile device 50 may not make a soft handover to theextension band 52 from the base station 53 since the mobile device 50will be jumping into a potential interference area, causing UL channelinterference. This situation may be detected and earlier decisions maybe made regarding handover to avoid UL channel interference.

FIGS. 4A and 4B show diagrams of uplink and downlink carrier pairingsaccording to example arrangements. Other arrangements are also possible.Uplink and downlink carriers from the existing band generally may befrequencies supplied by the same cell, but may be supplied fromdifferent cells. Similarly, uplink and downlink carriers from the newband may be frequencies supplied from the same cell (different from thecell supplying existing band frequencies). The A1, A2, A3, . . .represent different uplink/downlink frequency pairings. The frequenciesin the box for each band starting with “A”, may be controlled by oneoperator at the cell, the frequencies in the blank boxes controlled by asecond operator at the cell, and the frequencies in the darkened boxescontrolled by a third operator at the cell.

In these example embodiments, the existing uplink frequency band isshown to include frequencies starting at approximately 1920 MHz, theexisting downlink band to include frequencies starting at approximately2110 MHz, and the new uplink and downlink bands to include frequenciesstarting at approximately 2500 MHz. However, the present invention isnot limited by these frequency values but may be applied to any bands ofpossible frequencies. The frequencies being shown in FIGS. 4A and 4B arefor illustration purposes only, and do not limit the scope of thepresent invention.

FIG. 4A shows an example arrangement where a mobile node (UE) may beconnected with a uplink carrier frequency from an existing uplink band60 and a downlink carrier frequency from an existing downlink band 62.The existing downlink carrier band 62 may be a core band from a cellclosest to the location of the mobile node. A network node may determinethat the mobile node should select a second downlink carrier, and directthe mobile node to start using a downlink carrier from frequencies in anew or different downlink band 64 (i.e., from a different cell). Themobile node may then use the uplink carrier from the existing uplinkband 60 and a downlink carrier from a new or different downlink band 64.

FIG. 4B shows an example arrangement where a mobile node may haveoriginally been using an uplink carrier from a new uplink band 66 and adownlink carrier from a new downlink band 68. The new uplink band 66 andnew downlink band may be from the same band of frequencies (e.g.,starting at approximately 2.5 GHz where some frequencies are used foruplink carriers and some for downlink carriers). In this exampleembodiment, a network node may direct the mobile device to switch overand use a different downlink carrier, but from the same band offrequencies as the original downlink carrier. The frequencies in the newuplink band 66 and the new downlink band 68 may be supplied by the samecell, or from different cells.

Before a mobile station can communicate with a base station, the mobilestation must acquire the code and frame timing of the base station. Eachbase station may broadcast its primary scrambling code without any datamodulation on a common pilot channel (CPICH). However, it is notpractical for a mobile station to search through all codes for each ofthe pseudo noise (PN) code phases, so base stations also transmitadditional synchronization channels. As one example, the primarysynchronization channel (P-SSC) may be a fixed sequence that istransmitted, for example, once per 2,560 chips, referred to as a slot.In a frame of 38,400 chips, there may be fifteen 2,560-chip slots. Bysearching for the P-SSC, the mobile station can acquire the slot timing.

After acquiring slot timing, the mobile station may turn to thesecondary synchronization channel (S-SSC), which transmits a sequencethat allows the mobile station to uniquely identify frame timing andnarrow the scrambling code down to a group of eight possibilities. Afteracquiring the S-SSC, the final step is to search the CPICH using theeight scrambling codes to determine which one is actually in use by thebase station.

In handover searching, each base station may broadcast the scramblingcodes of its neighbor base stations. Even though the mobile stationknows the scrambling codes of neighbor base stations, the mobile stationstill must still acquire the timing of the neighbor base stations beforeit can include the neighbor base stations in its active set. Stateddifferently, the UE may utilize the primary synchronized channel(P-SCH), the secondary synchronized channel (S-SCH) and/or the primarycommon pilot channel (P-CPICH) to find the timing of another cell andidentify a scrambling code to measure Ec/IO or RSCP. However, thissearch procedure makes measurements and handovers slow.

Embodiments of the present invention may not perform all of theabove-described search procedures in the case of co-sited carriersand/or when synchronization information is appropriately provided to theUE. That is, UEs making measurements on another carrier or handing overto another carrier may use this synchronization information to make thesearch process faster (and therefore make the handover faster). This maybe especially useful for operations involving an extension band (such asthe 2.5 GHz frequency band for downlink carriers), inter-frequencymeasurements for interference detection in the core band and handoversbetween bands (e.g. for load balancing or coverage reason).

Embodiments of the present invention may utilize the synchronizationinformation for fast and efficient measurement (Ec/IO or RSCP). This maybe especially useful in compressed mode measurements, which areperformed by stealing measurement time from the current active link datareception. Embodiments of the present invention may also utilize thesynchronization information for UE synchronization such as to savecompressed mode usage for handover (i.e., faster handovers).

The synchronization information of DL carriers may be indicated from thenetwork to the UE. This may be done in measurement control informationsuch as when neighbor cell information is provided by the network to theUE. This synchronization information may be a single bit that indicateschip synchronization based on the status of the bit. For example, thebit may be “1” to indicate chip synchronization and the bit may be “0”when there is no chip synchronization. The synchronization information(in the form of a plurality of bits) may also indicate the relativesynchronization (e.g., time difference) when the DL carriers aresynchronized but the chips are not synchronized (such as due todifferent antenna cable lengths). More specifically, when chipsynchronization is achieved for all neighboring cells of a particularcell, the synchronization information may be informed for allneighboring cells by a common bit, for example. Alternatively, if somecells are chip synchronized and some chips are not chip synchronized,then the synchronization information may be provided separately for eachneighboring cell. The synchronization (or co-siting) information may beeither one bit or several bits.

The synchronization information may be sent from the network to the UEas a dedicated message in measurement control information, as abroadcast message in system information (broadcast control channel(BCCH)) and/or as measurement control system information. Both themeasurement control and the measurement control system information maycontain neighbor cell information for intra-frequency andinter-frequency cells.

FIG. 5 is a flowchart showing operations according to an exampleembodiment of the present invention. Other embodiments, operations andorders of operation are also within the scope of the present invention.More specifically, in block 102, the network determines if it issynchronized and determines the type of information that will betransmitted. In block 104, the network may transmit the synchronizationinformation (e.g., one bit or a plurality of bits) from a base station.Although not explicitly discussed, other base stations may also betransmitting their respective synchronization information. In block 106,a mobile device may receive the transmitted synchronization information.In block 108, the mobile device may perform any of a number ofoperations based on the received synchronization information. Forexample, the mobile device may include mechanisms to decipher thereceived synchronization information (such as a bit or a plurality ofbits) and then perform an operation (through hardware and software)based on the received information. The operation may include, but arenot limited to, handover (such as between different bands) andinter-frequency measurements.

Embodiments of the present invention are also applicable to equippingneighbor cells with the synchronization information. Further, theco-siting information may be given between the current serving or activecell and the corresponding co-sited neighbor cell on the other band. Theco-siting information may also be given between an intra-frequencyneighbor cell A and inter-frequency neighbor B, which is co-sited withthe cell A.

In at least one embodiment, the synchronization information may include“reference time difference information.” TS 25.331, v3.13.0 (2002-12),the subject matter of which is incorporated herein by reference,discusses three different accuracy classes for “reference timedifference information.”

Embodiments of the present invention may reduce the need of DLcompressed mode usage, and may make UE measurements and handoverseasier. Embodiments of the present invention may allow the mobile deviceto directly perform level measurement for a co-sited inter-frequencycell. This may be faster than a three-step cell search procedure (P-SSC,S-SSC and P-CPICH) and then CPICH level measurements (Ec/IO or RSCP).

Any reference in this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention. The appearances of thephrase “in one embodiment” in various places in the specification arenot necessarily all referring to the same embodiment.

Although the present invention has been described with reference to anumber of illustrative embodiments thereof, it should be understood thatnumerous other modifications and embodiments can be devised by thoseskilled in the art that will fall within the spirit and scope of theprinciples of this invention. More particularly, reasonable variationsand modifications are possible in the component parts and/orarrangements of the subject combination arrangement within the scope ofthe foregoing disclosure, the drawings and the appended claims withoutdeparting from the spirit of the invention. In addition to variationsand modifications in the component parts and/or arrangements,alternative uses will also be apparent to those skilled in the art. Asone example, embodiments of the present invention are also applicable toCDMA systems other than WCDMA.

1. A network device configured to: determine synchronization informationindicating relative synchronization between a first co-sited downlinkcarrier in a core band and a second co-sited downlink carrier in anextension band; and participate in an inter-band operation initiated bya mobile station receiving said synchronization information indicatingrelative synchronization between said first and second co-sited downlinkcarriers.
 2. The network device as recited in claim 1 wherein saidnetwork device is configured to transmit said synchronizationinformation to a plurality of mobile stations in a cell site served bysaid network device.
 3. The network device as recited in claim 1 whereinsaid inter-band operation includes an inter-band handover.
 4. Thenetwork device as recited in claim 3 wherein said inter-band handoverincludes a blind handover from one band to another band.
 5. The networkdevice as recited in claim 1 wherein said network device is configuredto provide said synchronization information to said mobile station as astatus bit.
 6. The network device as recited in claim 5 wherein saidstatus bit indicates chip synchronization.
 7. The network device asrecited in claim 1 wherein said network device is configured to providesaid synchronization information to said mobile station as a pluralityof bits.
 8. A network device, comprising: means for determiningsynchronization information indicating relative synchronization betweena first co-sited downlink carrier in a core band and a second co-siteddownlink carrier in an extension band; and means for participating in aninter-band operation initiated by a mobile station receiving saidsynchronization information indicating relative synchronization betweensaid first and second co-sited downlink carriers.
 9. The network deviceas recited in claim 8 further comprising means for transmitting saidsynchronization information to a plurality of mobile stations in a cellsite served by said network device.
 10. A computer program productcomprising a program code stored in a computer readable mediumconfigured to: determine synchronization information indicating relativesynchronization between a first co-sited downlink carrier in a core bandand a second co-sited downlink carrier in an extension band; andparticipate in an inter-band operation initiated by a mobile stationreceiving said synchronization information indicating relativesynchronization between said first and second co-sited downlinkcarriers.
 11. The computer program product as recited in claim 10wherein said program code stored in said computer readable medium isconfigured to transmit said synchronization information to a pluralityof mobile stations in a cell site served by a network device.
 12. Amethod, comprising: determining synchronization information indicatingrelative synchronization between a first co-sited downlink carrier in acore band and a second co-sited downlink carrier in an extension band;and participating in an inter-band operation initiated by a mobilestation receiving said synchronization information indicating relativesynchronization between said first and second co-sited downlinkcarriers.
 13. The method as recited in claim 12 further comprisingtransmitting said synchronization information to a plurality of mobilestations in a cell site served by a network device.
 14. The method asrecited in claim 12 wherein said inter-band operation includes aninter-band handover.
 15. The method as recited in claim 12 furthercomprising providing said synchronization information to said mobilestation as a status bit.
 16. A mobile station configured to: receivesynchronization information indicating relative synchronization betweena first co-sited downlink carrier in a core band and a second co-siteddownlink carrier in an extension band; and perform an inter-bandoperation based on said synchronization information indicating relativesynchronization between said first and second co-sited downlinkcarriers.
 17. The mobile station as recited in claim 16 wherein saidmobile station is configured to conduct measurements relating to saidinter-band operation.
 18. The mobile station as recited in claim 16wherein said inter-band operation includes an inter-band handover. 19.The mobile station as recited in claim 18 wherein said inter-bandhandover includes a blind handover from one band to another band. 20.The mobile station as recited in claim 16 wherein said mobile station isconfigured to receive said synchronization information as a status bit.21. The mobile station as recited in claim 20 wherein said status bitindicates chip synchronization.
 22. The mobile station as recited inclaim 16 wherein said mobile station is configured to receive saidsynchronization information as a plurality of bits.
 23. A mobilestation, comprising: receiving synchronization information indicatingrelative synchronization between a first co-sited downlink carrier in acore band and a second co-sited downlink carrier in an extension band;and performing an inter-band operation based on said synchronizationinformation indicating relative synchronization between said first andsecond co-sited downlink carriers.
 24. The mobile station as recited inclaim 23 further comprising means for conducting measurements relatingto said inter-band operation.
 25. A computer program product comprisinga program code stored in a computer readable medium configured to:receive synchronization information indicating relative synchronizationbetween a first co-sited downlink carrier in a core band and a secondco-sited downlink carrier in an extension band; and perform aninter-band operation based on said synchronization informationindicating relative synchronization between said first and secondco-sited downlink carriers.
 26. The computer program product as recitedin claim 25 wherein said program code stored in said computer readablemedium is configured to conduct measurements relating to said inter-bandoperation.
 27. A method, comprising: receiving synchronizationinformation indicating relative synchronization between a first co-siteddownlink carrier in a core band and a second co-sited downlink carrierin an extension band; and performing an inter-band operation based onsaid synchronization information indicating relative synchronizationbetween said first and second co-sited downlink carriers.
 28. The methodas recited in claim 27 further comprising conducting measurementsrelating to said inter-band operation.
 29. The method as recited inclaim 27 wherein said inter-band operation includes an inter-bandhandover.
 30. The method as recited in claim 27 wherein said receivingincludes receiving said synchronization information as a status bit.